1. Field of the Invention
The present invention relates to a device for providing assistance in safe driving by measuring the state of a driver by utilizing an electroencephalogram.
2. Description of the Related Art
In recent years, in connection with accident prevention apparatuses related to automobile driving, methods of measuring a state of a driver and providing driving assistance based on the result of measurement have been under study.
Methods of inferring the state of a driver include an indirect method of acquiring a steering angle, changes in traveling velocity, and the like, which reflect the manner in which an automobile is being operated. With information that is easy to acquire from the device side, in combination with white line detection, for example, this method has enabled assistance such as evaluating driving stability.
There are also methods which directly measure a driver's state, rather than a vehicle's state. For example, there have been attempts of detecting a driver's act of looking aside or drowsiness by detecting the direction of the line of sight or the status of blinking with a camera which is aimed at the driver, for example.
Furthermore, as a method of directly measuring a driver's state, a method of measuring an electroencephalogram of the driver is possible. An electroencephalogram, which is a potential change on the scalp that is measurable of the head, is supposed to reflect encephalic activities, and may possibly be an optimum representation of a driver's state.
The present invention aims to provide a distraction detection apparatus concerning the driving of a driver. An attention status during the driving of a driver is one of the statuses that are difficult to establish from the vehicle status, e.g., steering angle, or from external measurements with a camera, for example. Thus, it is considered that detection of a distracted status can serve as effective information for assistance in safe driving.
An example of an existing application concerning attention detection is an invention disclosed in Japanese Laid-Open Patent Publication No. 2004-178367 (hereinafter referred to as “Patent Document 1”), for example. This is an invention of detecting attention allocation of a driver from the vehicle status and from the line of sight or face motion of a driver.
An invention disclosed in Japanese Laid-Open Patent Publication No. 2005-228003 (hereinafter referred to as “Patent Document 2”) is directed to a method where, by using a database previously storing a relationship between the brain activity status and the vehicle operation of a driver, activities within the brain are estimated from the behavior of a vehicle. Encephalic activities are estimated from vehicle operating information.
However, with Patent Document 1 above, it is difficult to cope with the type of distracted situation where the line of sight is aimed but attention is absent, for example.
According to Patent Document 2, since there is no one-to-one correspondence between the behavior of a vehicle and activities within the brain, it is believed that some ambiguity will be left in the result of estimation. For example, when a relatively slow braking operation occurs, it is impossible to distinguish whether the driver was thinking that there was enough leeway or the driver was driving absent-mindedly, unless measurements were taken of the driver at that point in time.
Thus, in the detection of distraction, more accurate measurement methods have been desired.